darcsEncodeWhite translates whitespace in filenames to a darcs-specific
format (backslash followed by numerical representation according to ord).
Note that backslashes are also escaped since they are used in the encoding.

Create a hashed file from a FilePath and content. In case the file exists
it is kept untouched and is assumed to have the right content. XXX Corrupt
files should be probably renamed out of the way automatically or something
(probably when they are being read though).

Run a TreeIOaction in a hashed setting. The initial tree is assumed
to be fully available from the directory, and any changes will be written
out to same. Please note that actual filesystem files are never removed.

Read a Tree in the darcs hashed format from an object storage. This is
basically the same as readDarcsHashed from Storage.Hashed, but uses an
object storage instead of traditional darcs filesystem layout. Requires the
tree root hash as a starting point.

Write a Tree into an object storage, using the darcs-style directory
formatting (and therefore darcs-style hashes). Gives back the object storage
and the root hash of the stored Tree. NB. The function expects that the Tree
comes equipped with darcs-style hashes already!